Supplements with good to strong evidence of achieving benefits to performance when used in specific scenarios
| Beta-Alanine | |
| Overview | Caffeine is a stimulant that possesses well-established benefits for athletic performance across endurance-based situations, and short-term, supramaximal and/or repeated sprint tasks. |
| Mechanism | Adenosine receptor antagonism; increased endorphin release; improved neuromuscular function; improved vigilance and alertness; reduced the perception of exertion during exercise29 48 |
| Protocol of use | 3–6 mg/kg of body mass (BM), in the form of anhydrous caffeine (ie, pill or powder form), consumed ~60 min prior to exercise49 Lower caffeine doses (<3 mg/kg BM, ~200 mg), provided both before and during exercise; consumed with a CHO source48 |
| Performance Impact | Improved endurance capacity such as exercise time to fatigue50 and endurance-based time-trial (TT) activities of varying duration (5–150 min), across numerous exercise modalities (ie, cycling, running, rowing and others)49 Low doses of caffeine (100–300 mg) consumed during endurance exercise (after 15–80 min of activity) may enhance cycling TT performance by 3%–7%.51 52 During short-term, supramaximal and repeated sprint tasks, 3–6 mg/kg BM of caffeine taken 50–60 min before exercise results in performance gains of >3% for task completion time, mean power output and peak power output during anaerobic activities of 1–2 min in duration,53 and of 1%–8% for total work output and repeat sprint performances during intermittent team game activity.54 55 |
| Further considerations and potential side effects | Larger caffeine doses (≥9 mg/kg BM) do not appear to increase the performance benefit,56 and are more likely to increase the risk of negative side effects, including nausea, anxiety, insomnia and restlessness.29 Lower caffeine doses, variations in the timing of intake before and/or during exercise, and the need for (or lack thereof) a caffeine withdrawal period should be trialled in training prior to competition use. Caffeine consumption during activity should be considered concurrent with carbohydrate (CHO) intake for improved efficacy.52 Caffeine is a diuretic promoting increased urine flow, but this effect is small at the doses that have been shown to enhance performance.57 |